billing.eunet.rs has no MX records.
Question and response
Question
dig billing.eunet.rs. MX
Answer
The response has no answer records.
Authority
eunet.rs. 3600 SOA ns.eunet.rs. hostmaster.eunet.rs. 2022122101 7200 1800 86400 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0